Vibration actuator

Abstract

A vibration actuator includes: a vibration body 1 including an elastic body 2 and an electric-mechanical energy conversion element 3 joined to the elastic body 2; and a contact body 4 that contacts the vibration body 1. The vibration body 1 and the contact body 4 move relative to each other in a predetermined direction. A vibration-damping member 25 is provided on a predetermined surface of the contact body 4 that is different from a contact surface that contacts the vibration body 1. The vibration-damping member 25 is constituted by a viscoelastic body or by combining the viscoelastic body and a reinforcement member.

1 . A vibration actuator comprising:
 a vibration body including an elastic body and an electric-mechanical energy conversion element joined to the elastic body; and   a contact body that contacts the vibration body,   wherein the vibration body and the contact body move relative to each other in a predetermined direction, and   wherein a vibration-damping member is provided on a predetermined surface of the contact body that is different from a contact surface that contacts the vibration body.   
     
     
         2 . The vibration actuator according to  claim 1 , wherein the vibration-damping member includes a viscoelastic body made of a material different from a material of the contact body. 
     
     
         3 . The vibration actuator according to  claim 2 ,
 wherein the vibration-damping member includes the viscoelastic body and a reinforcement member, and   wherein the viscoelastic body is interposed between the contact body and the reinforcement member.   
     
     
         4 . The vibration actuator according to  claim 3 , wherein the vibration-damping member has a multilayer structure in which a plurality of the viscoelastic bodies and a plurality of the reinforcement members are alternately arranged. 
     
     
         5 . The vibration actuator according to  claim 1 , wherein the vibration-damping member is provided on both of the predetermined surfaces that face each other. 
     
     
         6 . The vibration actuator according to  claim 1 , wherein the vibration-damping member is provided on a side surface connected to the contact surface. 
     
     
         7 . The vibration actuator according to  claim 1 , wherein the vibration-damping member is provided on a surface opposite to the contact surface. 
     
     
         8 . The vibration actuator according to  claim 1 , wherein an end portion of the vibration-damping member does not protrude further than the contact surface. 
     
     
         9 . The vibration actuator according to  claim 1 , wherein an end portion of the vibration-damping member protrudes further than the contact surface. 
     
     
         10 . The vibration actuator according to  claim 6 , comprising:
 a holding portion that holds the vibration body,   wherein a total dimension of the contact body and the vibration-damping member in a direction parallel to the contact surface is less than a dimension of the vibration body or a dimension of the holding portion in the direction parallel to the contact surface.   
     
     
         11 . The vibration actuator according to  claim 1 , wherein the contact body is annular. 
     
     
         12 . The vibration actuator according to  claim 1 , comprising a positioning structure for positioning the contact body and the vibration-damping member. 
     
     
         13 . The vibration actuator according to  claim 1 , comprising:
 a displacement-detecting portion that detects relative displacement of the contact body and the vibration body,   wherein the displacement-detecting portion includes a detector that moves together with the contact body or the vibration body and a scale that moves relative to the detector, and   wherein a part of the vibration-damping member constitutes the scale.   
     
     
         14 . The vibration actuator according to  claim 1 ,
 wherein a vibration mode excited in the vibration body is an out-of-plane bending vibration mode in which a plurality of nodal lines are generated in the predetermined direction, and   wherein a sum total of a length of the vibration-damping member in the predetermined direction is greater than or equal to ½ of a wavelength of a natural vibration mode excited in the contact body.   
     
     
         15 . The vibration actuator according to  claim 1 ,
 wherein a vibration mode excited in the vibration body is an out-of-plane bending vibration mode in which a plurality of nodal lines are generated in the predetermined direction, and   wherein a sum total of a length of the vibration-damping member in the predetermined direction is greater than or equal to a length of an interval between the nodal lines that are adjacent to each other.   
     
     
         16 . The vibration actuator according to  claim 1 ,
 wherein a vibration mode excited in the vibration body is an out-of-plane bending vibration mode in which a plurality of nodal lines are generated in the predetermined direction, and   wherein a sum total of a length of the vibration-damping member in the predetermined direction is greater than or equal to a center-to-center distance between two projecting portions that are provided on the elastic body and are caused to contact the contact body.   
     
     
         17 . The vibration actuator according to  claim 1 ,
 wherein a vibration mode excited in the vibration body is an out-of-plane bending vibration mode in which a plurality of nodal lines are generated in the predetermined direction, and   wherein the vibration-damping member is provided at a position including an antinode of a natural vibration mode excited in the contact body.   
     
     
         18 . The vibration actuator according to  claim 1 , wherein the vibration-damping member is joined to the predetermined surface. 
     
     
         19 . A contact body unit comprising:
 a contact body that contacts a vibration body; and   a vibration-damping member provided on a predetermined surface of the contact body that is different from a contact surface that contacts the vibration body.   
     
     
         20 . An actuator unit, wherein the vibration actuator according to  claim 1  is unitized by using an outer member, and a part of the contact body or a part of a vibration body unit including the vibration body is led to an outside of the outer member to allow connection of a load. 
     
     
         21 . An apparatus comprising the vibration actuator according to  claim 1 . 
     
     
         22 . The apparatus according to  claim 21 , wherein a plurality of the vibration actuators are arranged radially in a plane perpendicular to the predetermined direction. 
     
     
         23 . A multi-axis stage comprising:
 the vibration actuator according to  claim 1 ;   a fixed portion to which the vibration actuator is fixed; and   a stage that is connected to the contact body and moves in a predetermined direction relative to the fixed portion.   
     
     
         24 . An articulated robot comprising the vibration actuator according to  claim 1  as a driving source.